Safety clamp devices adapted to be attached to a workman's belt and having a friction plate or shoe which is moved into gripping engagement with a safety line if the workman falls have been known and in use for many years. See, for example, U.S. Pat. No. 3,317,971 issued to R. E. Meyer on May 9, 1967 and U.S. Pat. No. 3,492,702 issued to L. R. Stafford on Feb. 3, 1970. Such prior safety clamps have had a number of disadvantages and shortcomings. A primary problem has been the inability of prior safety clamps to satisfactorily meet the tool requirements of being freely slidable on a safety cable as a workman goes up and down a ladder, and yet quickly and positively clamp onto a safety line or cable when the workman falls. Moreover, known safety clamps have not been readily mountable on a safety cable at various vertical positions of desired use.
The safety clamp of this invention incorporates a combination of features which overcome the aforesaid difficulties encountered with previously known safety clamps. Foremost among such features are a cam mechanism which instantly urges a wedge plate through a cable clearance space into engagement with a safety cable under free fall conditions, and the mounting and actuation of the wedge plate so as to permit the friction force of a safety cable acting on it to draw it into very tight, gripping engagement with the cable.